Paid clinical trial participation — often called "chiken baito" (clinical trial part-time work) in Japan — does not actually pay a salary. What you receive is a "burden-alleviation payment" (futan keigen-hi), treated in the tax world as miscellaneous income that is not compensation for labor. It can run ¥7,000–¥10,000 per outpatient visit, or hundreds of thousands of yen for inpatient studies, and it is paid in full without withholding — which is why people often assume, wrongly, that "no tax applies." This article sorts out (1) the filing thresholds — the ¥200,000 rule for employees and ¥950,000 for those with no salary, (2) the ¥580,000 line at which a student stops being a parent's dependent, and (3) the risks of not filing — all using the latest figures after the 2025 (Reiwa 7) tax reform.
What the burden-alleviation payment is: a clinical trial is not a "part-time job"
A clinical trial (chiken) is a study conducted to collect the data needed for approval of a new drug, carried out under rules set by the government (GCP — the national standards for conducting clinical trials of pharmaceuticals). The money paid to participants is not a salary or fee: it is positioned as a "burden-alleviation payment" meant to lighten burdens such as travel to the site, time commitment and lifestyle restrictions. The amounts are deliberately designed "not to become an inducement to participate," and industry materials treat ¥7,000 per outpatient visit as the standard.
| Type | Typical amount |
|---|---|
| Outpatient type (per visit) | Around ¥7,000–¥10,000 |
| Inpatient type (per night) | Around ¥20,000–¥30,000. Long inpatient studies can total several hundred thousand yen |
* Amounts are rough guides based on information published by multiple clinical-trial recruitment organizations and differ by study and medical institution.
There are three tax points.
- There is no employment contract, so it is not employment (salary) income. Information sheets that university hospitals hand to participants state explicitly that it is "miscellaneous income under the Income Tax Act"
- It is normally paid in full with no withholding. Tax not being deducted does not mean it is tax-exempt — it means the system expects you to report it yourself
- From the payment, you can deduct directly incurred costs, such as transportation to the site, as expenses. Keep receipts and records
This article covers taxes only
It does not address whether to participate in a clinical trial (the study's content, effects on your body and so on). Make that decision yourself, based on informed consent (explanation and agreement) from the medical institution conducting the trial. This article does not encourage participation in clinical trials.
From how much do you need to file? A quick table by situation
The filing threshold is judged not on "how much you received" (revenue) but on your "income" after deducting expenses such as transportation. If you received ¥600,000 in burden-alleviation payments but spent ¥30,000 on transportation, your miscellaneous income is ¥570,000.
| Situation | When a tax return becomes necessary (guide) |
|---|---|
| Employees / part-timers settled by year-end adjustment | When your total income other than salary exceeds ¥200,000 a year (the so-called ¥200,000 rule). Clinical-trial miscellaneous income is judged combined with your other non-salary income, such as side jobs and point-earning activities |
| Full-time homemakers, people not working, students with no salary | If your total income is at or below the basic deduction, no income tax is due and no return is needed. From the 2025 (Reiwa 7) tax year, the basic deduction for people with total income of ¥1.32 million or less was raised to ¥950,000 (previously ¥480,000) |
| Sole proprietors / freelancers | Whatever the amount, include it in your annual tax return as miscellaneous income |
For the exact conditions of the ¥200,000 rule for employees (such as salaries from two employers) and how to file for side income in general, see our guide to filing a tax return for side jobs.
"Up to ¥480,000 is fine" is outdated information
The 2025 (Reiwa 7) tax reform revised the basic deduction: from the 2025 tax year onward, it is ¥950,000 for people with total income of ¥1.32 million or less (the change took effect on December 1, 2025 and applies from the 2025 tax year). Many explanations online still show the pre-reform "¥480,000," so be careful. Note, however, that the line for a parent's dependency is different (¥580,000), as explained below.
Even at ¥200,000 or less, resident tax filing is separate
The ¥200,000 rule is a special rule for national income tax only. Resident tax has no such rule, so even when you do not file an income tax return, a resident tax return to your municipality is in principle required. The resident-tax basic deduction also remains ¥430,000, so a single person generally owes resident tax once total income exceeds roughly ¥450,000 (it varies by municipality). Watch out for the zone where income tax is zero but resident tax still applies.
The line at which a student leaves a parent's dependency: part-time-job intuition does not apply
From the 2025 tax year, a child can stay within a parent's dependency (the dependent deduction) if the child's total income is ¥580,000 or less (previously ¥480,000). The trap here is that the employment income deduction cannot be used against clinical-trial burden-alleviation payments.
- Part-time salary only: the employment income deduction (minimum ¥650,000) applies, so you stay within dependency up to ¥1.23 million in salary (¥1.23 million − ¥650,000 = income of ¥580,000)
- Clinical trials only: there is no such deduction, so you leave dependency the moment miscellaneous income exceeds ¥580,000 — an amount you can reach with a few long inpatient studies
- Combining both: part-time salary of ¥900,000 (employment income ¥250,000) + clinical-trial miscellaneous income of ¥300,000 = total income ¥550,000, still within dependency. If the trial income rises to ¥340,000, the total becomes ¥590,000 and you are out
For children aged 19–22, the special deduction for specified relatives, newly created in 2025, tapers the parent's deduction gradually up to income of ¥1.23 million even after you pass ¥580,000 — so it is no longer "one yen over and the parent's deduction drops to zero at once" (the full deduction is ¥630,000). Even so, crossing the dependency line can affect the parent's tax burden, benefits and the dependent allowance at the parent's workplace, so if you look likely to cross it, the safe move is to tell your parents in advance. For the full picture of part-time work and dependency, see our guide to student part-time jobs and parental dependency.
Health-insurance dependency (the ¥1.3 million standard) is a separate test
Tax dependency and health-insurance dependent status (the so-called ¥1.3 million wall) are different systems. How a one-off payment like a clinical trial is treated varies by insurer — health insurance societies, Kyokai Kenpo and others — so if you will receive a large amount, check with the insurer at your parent's workplace.
How it differs from health-food and beauty product monitoring
Clinical trials are easily confused with paid "monitor" gigs for health foods, cosmetics and the like. In both cases the money received is in principle miscellaneous income, but the nature differs.
| Item | Clinical trial (pharmaceuticals) | Health-food / beauty monitors etc. |
|---|---|---|
| Legal basis / oversight | Clinical trial under the Pharmaceuticals and Medical Devices Act and GCP | Private research or promotional activity (outside GCP) |
| What you receive | Burden-alleviation payment (not compensation for labor) | Honorarium or fee (sometimes close to payment for services) |
| How it is paid | Usually bank transfer, no withholding | Cash, but sometimes points or products |
| Tax treatment | Miscellaneous income | In principle miscellaneous income (even points or products can be taxable as an economic benefit) |
Note that "I got points, not cash, so it doesn't count" does not hold. The tax treatment of points is covered in detail in our guide to point-earning and flea-market taxes. Monitor honoraria and clinical-trial payments are combined when applying the ¥200,000 rule.
"It's a bank transfer, so no one will find out" does not work: payment records and the risks of not filing
Burden-alleviation payments are made by bank transfer from medical institutions or site management organizations, so the payer keeps records of who was paid and how much. Statutory reports such as payment records (shiharai chosho) may be submitted to the tax office, and under the My Number system there is a real possibility that your income will be identified from payment records.
The penalties for failing to file when you should are not light.
- Non-filing penalty tax — if you file only after a tax audit, a surcharge of 15% applies on tax due up to ¥500,000, 20% on the portion over ¥500,000 up to ¥3 million, and 30% above ¥3 million. File voluntarily before the audit notice arrives and it is reduced to 5%
- Delinquency tax — interest-like delinquency tax accrues according to the number of days past the original due date
- File as soon as you notice — a voluntary late return does the least damage, and in certain cases, such as filing voluntarily within one month of the statutory deadline, the non-filing penalty is not imposed at all
What to do today
What to do today
- List the burden-alleviation payments you received (or will receive) this year, using your bank records and the documents you got when participating. Gather your records and receipts for transportation to the site as well
- Compare the threshold for your situation (employees ¥200,000, no salary ¥950,000, dependent students ¥580,000) with your expected miscellaneous income after expenses
- If you are a dependent student likely to exceed ¥580,000, tell your parents today (it affects their dependent deduction, dependent allowance and health insurance)
FAQ
Q. Isn't the clinical-trial burden-alleviation payment tax-free?
A. No, it is not tax-free. Because it is not compensation for labor it is not salary, but under the Income Tax Act it is taxable as miscellaneous income. It arrives in full without withholding not because "no tax applies," but because the system expects you to file yourself when required.
Q. I'm an employee and my clinical-trial income is ¥200,000 or less a year. Do I need to do anything?
A. You do not need to file an income tax return, but the ¥200,000 rule is a special rule for income tax only. Resident tax has no such rule, so a resident tax return to your municipality is in principle still required. Also, if you file an income tax return anyway — for the medical expense deduction, for example — you must include the clinical-trial income even at ¥200,000 or less.
Q. I'm a student. Up to how much can I stay my parent's dependent?
A. From the 2025 tax year, the line is total income of ¥580,000 or less. Because the employment income deduction cannot be used against clinical-trial payments, with trials alone the guide is miscellaneous income of ¥580,000 after expenses. If you also have a part-time job, the test is "salary revenue minus ¥650,000" plus your clinical-trial miscellaneous income. For ages 19–22, the special deduction for specified relatives keeps part of the parent's deduction in stages even past ¥580,000.
Q. I should have filed but forgot. What should I do?
A. File a late return as soon as possible. If you file voluntarily before you are contacted about a tax audit, the non-filing penalty tax is reduced to 5%. After an audit, up to a 30% non-filing penalty applies, plus delinquency tax.
References (sources)
* Figures and rules are based on information as of August 2026. Burden-alleviation payment amounts are rough guides based on information published by multiple clinical-trial recruitment organizations and differ by study and institution. This article is general information and does not encourage participation in clinical trials. For individual tax decisions, consult a tax office or tax accountant.